IS I -5047 ( Part III ) - 1979 Indian Standard ( Reaffirmed 2001 ) GLOSSARY OF TERMS RELATlNG TO ALUMINIUM AND ALUMINIUM ALLOYS PART III GEOMETRICAL PROPERTIES AND TOLERANCE, STRUCTURAL AND SURFACE DEFECTS ( First Reprint FEBRUARY 1990 J I UDC 669.71-4:531.7:001.4 @ Copyright 1979 BUREAU MANAK OF BHAVAN, INDIAN STANDARDS ZAFAR MARG 9 BAHADUR SHAH NEW DELHI 110002 Cr I Dscember 1979 IS: 5047 ( Part III ) - 1979 Indian Standard GLOSSARY OF TERMS RELATING TO ALUMINIUM AND ALUMINIUM ALLOYS PART III GEOMETRICAL PROPERTIES AND TOLERANCE, STRUCTURAL AND SURFACE DEFECTS and Their Alloys Indian Light SH~I B.K. Metals Sectional Aluminium Committee, Co Ltd, Calcutts SMDC 10 Chaimum MUBTHY Mmbrrs RIprrs&ine Aluminium Corporation of India Ltd, Calcutta Hindustan Aluminium Corporation Ltd, Renukoot, Dirtrict Mirzapur Directorate of Technical Development aad ProducdHBI s. N. CannknJ~a tiodr Air ), Air Headquarters, New Delhi Integral Coach Factory, Perambur, Madras CHEMIST B METALLURQIST Premiei Automobiles Ltd, Bombay Suar D. M. DAVER SHBI A. T. BOBATE ( A&m& ) Cable and Conductor Manufacturers' Associatiou SHSI P. U. DEORA of India, New Delhi National Test House, Calcutta\ SHRI A. GEOSH Sam B. N. SARXAII ( Alhrnatr ) Indian Aluminium Co Ltd, Calcutta Smu N. GOPALKBISHNAN SERI A. K. HAJBA ( Alhmub ) Indian Standard Metal Co Ltd, Bombay SHBI F. A. A. JASDANWALLA SHUI C. CHATTILBJEE ( Al&malr ) JOINT DIRE~TOB ( MET )-P.&f, Ministry of Railways RDSO, LUCKNOW C"E"t6"', ,*s ~Mnrc~~&;;~;~ 1 * JAYALPUR ( Allrrnota I ) DEPUTY DIRE~OR, STANDABDS ( tire )-II, RDSO, LlJOXNOW(~~fdUI~r~~) Aluminium Industries Ltd. Madras Sam P. M. JOSEPH Ministry of Defencc ( R & D ) SEBI M. K. Jose1 SEBI I. N. BH~TIA ( Alternnlr ) &RI &ax V. D. AQARWAL V. K. AQEAWAL ( Continwd on pare 2 ) I 1 cupyrigh~1979 BUREAU OF INDIAN STANDARDS Thin publication ir protected under the In&n capjriglrrAct ( XIV of 1957 ) snd reproduction in whole or in part by my meam except with written permission oftbe publisher till be deemed to be 81) infringement of copyright unda the mid Act. 1 IS ,: 5047 ( Part IH ) - 1979 ( L'onfiked from pop 1 ) Members Snnx M. L. KAUL LT-COG,D. B. BRAN ( Alternate SHRI S. L. KIIA~NA SRRI M. Y. BOILKAR( Alternate DR D. KIJDUR Da R. KUMAJ~ Rejvcrmting Bharat Aluminium Co Ltd, New Delhi ) Ministry of Defcnce ( DC1 ) ) Malaviya Regional Engineering College, Jaipw National Metallurgical Laboratory ( CSIR ), lamshedpur DIZ MANJIT SINQH ( Alternate ) Electrical Manufacturing Co Ltd, Calcutta SHRI 0. P. MATHUIX Dire$;t&gneraloT Technical & Development, Suer L. MISHRA Directorate General, Ordnance Factories, Calcutta SRRI D. Y. MO~HE SHHI B. D. BJSWAS ( Alfemale ) Hiiidustan Aeronautics Ltd ( Bangalore Division ), DJZ KRISKINA DAS NAIR Bangalore SHUI V. S. L. PATRIKAE ( Allcrnak ) Jindal Aluminium Ltd, Rangalore Ssnr K. R. RAGHUNATE Bharat Heavy Elcctricals Ltd, Hydcrnbad SEHI U. MOHAN RAO DR K. K. SEN GODAN ( Alternate ) India Government Mint ( Ministry of Finance ), SHRI P. M. Rnu Hydcrabad Planning Commission, New Delhi REPRESENTATIVE India Pistons Ltd, Madras SHRI M. S. SRSIIADRI Jecwanlal ( 1929 ) Ltd, Calcutta SHRI D. H. SHAH SHHI N. H. SHAH ( Alternate ) Madras Aluminium Co Ltd, Mcttur Dam SHRI N. SHANMTJGHAM Ministry of Stcrl & Mines SRRI C. SEARMA Central Electrochemical Research Institute ( CSIR ), SHRI B. A. SHENOI Karaikudi SHRI P. S. DRSIKAX ( Al&mate ) Directorate General of Supplies & Disposals, SHRI K. M. TA~EJA New Delhi SH~I S. B. GUPTA ( Alternate ) Director General, X.73 ( &-o&o Member ) SHRI C. R.`RAMA RAO, Director ( Strut & Met ) Deputy Saar B. MTJIKHEBJI Director ( Metals ), ISI Glossary and Alloy Designations Convex SERI Panel, SMDC 10/P-12 B. K. MURTHY i%fembsrr Indian Aluminium Co Ltd, Calcutta SHSI N, COPALI~.RIB~~~P( Rlfrrnotr to Shri B. K. Murthy ) Hindustan Aluminium War V. K. Aoa~wu ( Dirt Miraapur ) Corporation Ltd, Rcnukot 2 IS I 5047 ( Part III ) n 1979 Indian Standard GLOSSARY OF TERMS RELATING. TO ALUMINIUM AND ALUMINIUM ALLOYS PART III GEOMETRICAL PROPERTIES AND TOLERANCE, STRUCTURAL AND SURFACE DEFECTS 0. FOREWORD 0.1 This Indian Standard ( Part III ) was adopted by the Indian Standards Institution on 23 July 1979, after the draft finalized by the Light Metals and Their Alloys Sectional Committee had been approved by the Structural and Metals Division Council. 0.2 This standard ( Part III ) has been prepared to making the glossary of terms for application in the aluminium industry more comprehensive by including the terms connected with special types of wrought metals, plant and operations, thermal treatment, control and testing, finishing, geometrical properties and tolerance, structural and surface defects; etc. It is hoped that this comprehensive standard on glossary of terms for aluminium and its alloys will help in estabilishing a generally recognized usage for various terms encountered in the aluminium industry and eliminate any confusion which may sometimes arise due to individual interpretation of terms used in the industry. 0.3 This standard is being issued in three parts covering different subjects in a logical sequence. This part dealing with geometrical properties and tolerance, structural and surface defects forms Part III of the series. The other parts in the series are given below: Part I Unwrought and wrought metals ( main and special types ) Part II Plant and operations, thermal treatment, control and testing, finishing 0.4 In the preparation the following: of this standard assistance has been and The derived from BS 3660 : 1963 Glossary of terms for aluminium alloys. British Standards Institution. Nomenclature for aluminium mill products. Association of USA. 3 . aluminium Aluminium IS : 5047 ( Part III ) 1. SCOPE l 1979 1.1 This standard ( Part III ) defines commonly used terms in the aluminium industry relating to geometrical properties and tolerance, structural and surface defects and also some general terms not covered in other two parts of the Glossary. 2. TERMS AND DEFINITIONS 2.1 Geometrical 2.1.1 Tolerance characteristic. 2.1.2 Length working. Properties and Tolerance amount which of deviation lies in the from a specified direction of final An allowable dimension That 2.1.3 Width - The major tion of final working. 2.1.4 product dimension which lies transverse to the dirccedge of a in Straightness - The extent to which approaches a straight line. the axis or the lateral 2.1.5 Lateral Curvature ( Edge Cu~atur~ ) - The the form of an'arc, of an edge from straightness. 2.1.6 Bow - Deviation following an arc. from a straight departure, line of a length of a product 2.1.7 Lateral Bow - Deviation ( sometimes called camber ). 2.1.8 Longitudinal Bow the plane of a sheet. 2.1.9 T~ansvcrse Bow - of a longitudinal curvature edge from straightness along the length in A longitudinal Curvature across the width of sheet or foil. as n bul~c of a <)I' 2.1.10 Buckle - A distortion of the surface of sheet such a wave usually tr;msverse to the direction of rolling. 2.1.11 Flatness - The approaches a true plane. extent to which the across surface the width product 21.12 Concavity - An inward curvature ofa rolled or extruded product. 2.1.13 Convexity - An outward curvature of a roIIcd or extruded product. of a surface across the wicltll of a surf:lce faces of a orientation of two adjacent 2.1.14 Angle - The relative section generally measured over the full length of both. 4 IS : 5047 ( Part III ) - 1979 2.1.15 Angularity - Conformity to or deviation from, dimensions in the cross section of a sha'pe or bar. 2.1.16 Twist - Torsiolal length of a product. 2.1.17 Corner Radius a product are tangential. The deviation radius of the transverse of an arc to which specified angular axis along adjacent of a round throughout is established the' sides of tube, the by ?A.18 Ovality - The departure bar or wire, from a true circle. of the cross section 2.1.19 Concentricity - Uniformity of wall thickness cross section of a tube. The tolerance on concentricity the wall thickness tolerance. 2.1.20 Mean Wall Thickness - The sum measured at the ends of any two diameters by four. 2.1.21 Mean Diameter - The average meter at right angles to each other. of the wall thickness at right angles, and of tube divided of two measurements of the dia- from a common centre as, for' exampie, 2.1.22 Ecccntiicity - Deviation The difference between the the inner and outer walls of a round tube. mean wall thickness and minimum or maximum wall thickness at any one cross section. The permissible degree of eccentricity can be expressed by a plus and minus wall thickness tolerance. oue 2.i.23 Sliding Fit - The ability of two pieces of metal, internal and the other external bearing surfaces of complementary to fit and move easily one wlthin the other. 2.1.23.1 Snap & minor pressure. 2.1.24 Splice - having shape, To fit one metal uniting piece with another two webs. by applying The end joint 2.1.25 Squareness - Characteristic meeting at 90 degrees. 2.1.26 llteb - A connecting shapes and forgings. 2.1.27 Cet1ter of a sheet. 2.1.28 Fillet - of having between adjacent sides or planes or bosses on and edges element ribs, flanges between middle The difference A concave in thickness between junction two surfaces. to provide 2.1.29 Rib stiffening. An elongated projection 5 on a shape or forging 2.2 Structural and Surface Defects 2.2.1 Non-heat Treatable Material - which does not respond to solution and which therefore requires cold mcctlanical propcrtics. 2.2.2 11'ork Hardening defornlation. Effecting Pure metal or that type of alloy treatment*or precipitation treatment working filr the improvement of its an increase in tensile strength by cold 2.2.3 I-lent-Treatable Alloy - A type of alloy which will respond to solution trcatrncnt or prccipitntion trcntmcnt or both, thus permitting enhanced mechanical properties to bc secured. 2.2.4 Mass Efect - The effect of the size and shape the rate of heat transfer duCng quenching resulting mechanical properties frorn the outside to the centrr. of an article in variations on in 2.2.5 Free Cultiq Alloy - An alloy which by virtui: of its chrmical composition and condition, has constituents in a spheroidal form distributed throughout the rnctal which act as chip breakers. 2.2.6 Natural Oxide Film - The self-healing film or skin of aluminium oxide which forms naturally on aluminium and which is relatively inIpervious to atmos~~hcric attack. 2.2.7 Cold Shut a) A linear discontinuity in a cast surface caused when mrelirig streams of molten metal fail to merge prior to solidification: b) A forging defect developed by metal flowing into i\ section from two directions, resulting in a discontinuity at the junction. wile, 2.2.8 Roll Mark - A defect on plate, sheet, stri? or flattened repeated at regular intervals and caused by an imperfection in the roll SUIface. 2.2.9 Pinch Marks direction of rolling. Pressed-in folds generally marks running associated parallel with to the differenduring between 2.2.10 Pack Marks - Small superficial tial metal flow in pack rolling. scratches 2.2.11 Block Marks - Short longitudinal rewinding of sheet, strip or foil, resulting from relative adjacent wraps of the coil. 2.2.12 extruded 2.2.13 product introduced movement Reeling Marks - or drawn ilnpressed products Superficial spiral markings present on round which have been straightened by reeling. of a Stretcher Grip Marks -Transverse indentation at the ends by the grips of the stretching machine. G IS : 5047 ( Part III ) - 1979 2.2.14 Conveyor Marks - sheet as a result of contact Scratches and pits occurring on one side of a with cables or other means of conveyance. surface spots 2.2.15 Tra$c Marks ( Transit Abrasions ) - Small black caused by the attrition of adjacent surfaces during transit. 2.2.16 Drawn-in-Scratch - A scratch occurring process and subsequently drawn over making touch. during the fabricating it relatively smooth to markings taking the form of 2.2.17 Herring Bone Streak - Superficial alternate light and dark bands forming a V or. W pattern across the width of strip-mill rolled material. 2.2.18 Friction Scratches - Short longitudina! during coiling or reeling of sheet, strip or foil between adjacent wraps of the coil. 2.2.19 Broken Edge - scratches by relative splits or tears. introduced movement Edge containing cracks, 2.2.26 Broken Surface - A surface having running normal to the direction of working. 2.2.21 Broken Mott Finish of pack rolled foil. An uneven innumerable minute cracks surfaces finish on the matting 2.2.22 Surface Bloom - Surfxe discoloration which may develop on aluminium during exposure to moist atmospheres or during thermal treatment. 2.2.23 Telescoping - Transverse slipping of successive layers of a coil of sheet or foil's0 that the ends of a coil are conical rather than flat. 2.2.24 Whip Mark - Markings normal to the direction of rolling, as it ecters the rolling mill. 2.2.25 oxidation Oxide Discoloration - on a sheet surface generally running resulting from a whipping of tbe sheet of the material surface due to occurring from the from the by the during thermal DLcoloration treatment. discoloration 2.2.26 Dl#usion Staining or Streaks - Patchy during the thermal treatment of clad material and resulting complete penetration ot the cladding by alloying constituents core and their reaction with air or water. 2.2.27 Caustic Stain - A etching action of caustic. superficial surface blemish caused 2.2.28 Oil Stainitlg - Staining associated with the partial of residual lubricant during thermal treatment. 7 decomposition IS : 5047 ( Part III ) - 1979 surface oxidation due to the 2.2.29 W&r Staining - Superficial reaction of water films held between closely adjncent metal surfaces such The appearance varies as between wraps of a coil or sheet in a stock. from iridescent iu mild cases to white, grey or black in more severe instances. 2.2.30 Ifcut Trcut Stain - A discoloration surlier tluriug thermal treatlnrnt. 2.2.31 I.&U crossed lines. Lines Strain markings due to oxidation in the form of of the metal stepped criss surface distortion in the 2.2.32 Stretcher Strain AIarkir!,o.r - Permanent fi)rm of flamboyant patterns or Liiders lines which appear when m,lteri;ds The onset of these markings varies according to the tylje are stretched. of the material ilnd the degree of stretching. 2.2.33 Ripple - A surface effect in the form of a very slight rrpeatrd transverse wave or shadow mark, sometimes encountered with rolled or drawn products. Of' 2.2.34 Surface Texturr - The quality of a surface roughness as assessed by using a profilometer. according to its degree spaced superficial transverse markirlgs 2.2.35 Chatter - Regularly produced by vibration between the metal and the tools during !;ll)ric.ntion, resulting in non-uniform surface reflection and bri&tness. 2.2.36 adhesion surface roughness Pick-Up - An inegular between the forming tools and the metal. caused by iIltrrmitteut 2.2.37 Roll Coating Pick-Up - A surface belmish on rolled material resulting from aluminium oxide transferring frotn the roll to the sheet surface giving a speckled appearance. roughening resulting 2.2.30 Orange Peel EJect - Surface deformation under tension of coarse-grained material. 2.2.39 Pit A sharp depression in the surface. from the 2.2.40 Speed Crtzcking ( CVOSS Hatching Ftalhcring ) - Transverse surface cracks produced by excessive extrusion speed and/or extrusion emergence temperature. 2.2.41 attrition. 2.2.42 groove. Abrasion ( Scratches ) ( Scuff Marks ) Cougr Mechanical damage 8 taking Surface damage caused by the form of an isolated deep IS : 5047 ( Part III ) - 1979 2.2.43 Nick - A surface cut, indentation or notch. 2.2.44 Scort or edge discontinuity in the form of a slight A deep scratch. 2.2.45 Die Lines - Continuous longitudinal lines formed on extruded or drawn products by minor irregularities on the bearing surfaces of the die. 2.2.46 Die Scores - Relatively deep continuous longitudinal extruded or drawn products caused by the build up of aluminium bearing surface of the die. 2.2.47 of metal 2.2.48 2.2.49 Lap - lines on on the folding Fold Crease - An open ended surface over during mechanical A deep lap. lap. discontinuity working. formed as a result A shallow 2.2.50 chop - A lap formed at the base of a near vertical forging by the downward movement of the top die. face ofa die arising 2.2.51 Stop Mark - A transverse periphera1 ridge on a product from a stoppage during rolling, extrusion or drawing. 2.2.52 2.2.53 2.2.54 Bite Mark - A stop mark on rolled A stop mark on extruded products. or drawn products. plane. out between out between main edge, body of the the a Die Mark h/ink - A localised deviation from an intended squeezed squeezed the at an 2.2.55 Fin - A thin flange of excess metal rolls in the production of hot rolled rod. 2.2.56 Flash - A thin flange of excess metal die faces in the production of a die forging. 2.2.57 forging. Lug A thin, narrow projection from ragged 2.2.58 Burr - A sharp associated with a cutting operation. 2.2.59 Burred Edge - A thin foil resuIting from shearing. turned projection down edge generally or on sheet, of the extrusion parent piece 2.2.60 Spill ( Sliver ) - A thin elongated adhering imperfectly to the surface of a product. metal lateral displacement of any 2.2.61 Mismatch ( Offset > - The maximum point in that part of a forging formed by one die, from its correct position relative to the part of the forging formed m the other die of the pair. 9 IS : 5047 ( Part III ) - 1979 2.2.62 Lock all in one plane. A condition in which the parting line of a forging is not on the surface of the metal caused by the 2.2.63 Blister - A raised.area expansion of a gas ( for example, hydrogen ) enclosed in a sub-surfice void. 2.2.64 Coating Blisttr - A blister in the coating of an alclad or a clad product. 2.2.65 Adhesion or Bond Blister - A blister associated in metallurgical bending between the coating and material. with discontinuity the core in clad from the parent 2.2.66 Dorrblc Skin - A thin surface layer separated material by a film of oxide or other foreign matter and originating during estrusion. 2.2.67 Lamination - Internal surfaces of a sheet or plate. 2.2.68 metal. Inclusion - crack body that aligned accidentally parallel to the principal within the the A foreign entrapped metal 2.2.69 Shrinkage - Contraction hot working temperature. 2.2.76 Segregation -Localized CoustituentS of an alloy. 2.2.71 Sean1 - A line juncture of two or more edges by pressure, occurs when cools from or more concentration of one of the resulting from the deliberate bonding fusion or mechanical interlocking. 2.2.72 Extrusion Defect ( Piping) ( Coring ) - An internal defect occurring at the back-end of an extrusion due to oxide from the surface of the cast billet being extruded into the product. 2.2.73 Extrusion Seam -A seam in tube, pipe and hollow shape resulting from the pressure bonding of two or more edges in the course of extrusion through a spider or port hole die. 2.2.74 Pi)kzx An axial discontinuity in a round swaged bar. 2.2.75 Critical Working - Cold working of metal to such a degree as to give rise to very coarse grain on subsequent annealing or solutiott trcatmcnt. 2.2.76 Eqtriaxcd Grains - Grains or crystals which have approximately the same dimensions in three axial directions. 2.2.77 Grain Growth -The coarsening of the crystal structure occurring under certain conditions of heating or combined heating and cold working. 10 IS I 5047 ( Part- III ) - 1979 2.2.78 Gf~h~7~~ - Elongation of working, revealed by etching of the crystal structure a polished section. in the direction nonuse of 2.2.79 Multi-hole E$ect ( Crescent Effect ) - A characteristic concentric configuration of grain structure resulting from the multihole dies. 2.2.80 Peripheral Coarse Grain ( Pheripheral Grain Band ) - An area of recrystallized grains at the periphery of an extruded product, which has lower properties than the non-recrystallized core. 2.2.81 Extrusion Eject - The .persistence of an essentially non-recrystallized core in the majority of alloys which have been extruded and solution treated. This results in substantially higher tensile properties in the longitudinal direction than are obtained with .the same alloys when in other wrought forms. 2.2.82 Hot Shortness -A tendency Non-uniform to brittleness while hot. within the metal in the out. ofan 2.2.83 Internal Stress after fabrication. forces retained stress as may be left 2.2.64 Residual Stress - Such internal finished product after stress relieving operations have been carried 2.2.85 Liquation - Fusion of the lower-melting-point alloy during hot working or thermal treatment. constituents treatment at too high a temperature 2.2.86 Over- Ageing - Precipitation or for too long a period, resulting in the impairment of the tensile It may sometimes be applied deliberately ta improve properties. resistance to stress corrosion. 2.2.87 Under-Ageing- Precipitation treatment at too low a temperature or for too short a period, resulting in failure to attain maximum' tensile properties. 2.2.88 liquation 2.2.89 markings in such a way that Overheating - Heating to a high temperature occurs to the detriment of the mechanical properties. to such a degree that stretcher Overstretching - Stretching develop or the grainstructure of the metal is revealed. partial bending. elastic recovery of materials strain 2.290 Spring Rack -The deformation, for example, after cold 2.2.91 Ruling Thickness -The across which the time of heat operations. 2.2.92 Belly near the sides. A fullness dimension of a bar, forging or component transfer is the longest in heat treatment of foil either at the centre or in cross section 11 1s I 5047 ( Part III ) - 1979 2.2.93 Dished distortion during from flatness Edges - Departure shearing, slitting or blanking. associated with .edge from flatness represented 2.2.94 Wavy Edges - Departure ted or wave-like formation of the edges of a rolled product centre area remains flat. 2.2.95 Earing - Wavy projections articles, due to variation in directional around the rim properties. by a corrugain which the drawn of a deep projections formed in the course of 2.2.96 Ears - Wavy symmetrical deep drawing or spinning as a result of directional properties or anisoEars occur in groups of 4 or 8 with the peaks of the tropy in sheet. projections located at 45" and/or 0" and 90" to the rolling direction for Degree of earing the cold worked and annealed materials respectively. is the ditference between average height at the peaks and valleys divided by average height at the valleys multiplied by 100 and expressed in percent. from flat2.2.97 Oilcan Efect - In sheet or strip a localized departure ness which behaves in a similar manner to the diaphram of an oilcan under alternating pressure. of thickness or diameter of a solid 2.2.90 O$ Gauge - Deviation product, or wall thickness of a tubular product from the standard or specified dimensional tolerances. 2.2.99 Grown ( Middle ) - The difference edge and the centre of a rolled product. in thickness between Thinner line. Thicker line. resulting one than than from a drop forging or stamping. 2.2.100 Under-Strength -of the design thickness when measured normal to the parting 2.2.101 Over-Strength - of a drop forging the design thickness when measured normal 23.102 lubricant or stamping. to the parting residue Lubricant Residue - The carbonaceous burned on the surface of a forged part. 2.2.103 Parting Line ( Flash Line ) - The line on a stamping or pressing corresponding to the plane of contact between the dies used in the process of manufacture. 2.2.104 Flow Lines - Lines about by incomplete levelling 2.2.105 Flow Through the base of a rib resulting on the surface of the point. of pointed sheet, brought flows past A forging defect caused when metal in rupture of the grain structure. 12 18:9047(PastIrI)-1979 The angular 2.2.106 Draft Angk - In the design of die forgings. departure from the direction in which the blow is struck of surfaces which are nominally parallel with that direction. 2.2.107 Natural Draft An& - The minimum draft angle compatible with consistent freeing of the top die from the product during forging. 2.2.198 Matching Draft Angle - A draft angle greater than the natural draft angle necessitated on forgings unequally disposed about the parting line to provide coincident edges on that line. 2.2.109 Suck-in- A defect caused when one face of a forging is suckedin to 611 a projection on the opposite side. 2.2.110 Forging Plane - A plan view of a dummy showing the manner in which it should be positioned in the dies. 2.2.111 Knock-Out Mark - A small solid protrusion or circular fin on a forging, resulting from the depression of a knock-out fin under forging pressure or inflow of metal.between the knock-out fin and the die. 22.112 Random Lengths limits of length. Cut pieces usually specified between wide 2.2.113 Equivalent Round- The diameter of a circle whose area is equal to the cross sectional area of an extruded or drawn section. 2.2.114 Circumscribing Circle - A circle which will just contain the cross-section of an extrusion usually designated by the size of its diameter. wound layer on layer across the width 22.115 Layer Wound Coil -wire of a spool, where the width of the coil is greater than the width of the material. 2.2.116 Pancake Coil - Narrow strip and flattened wire wound layer on layer where the width of the coil is equal to the width of the material. 2.2.117 Forging Drawing - A drawing showing the agreed contour of a forging and usually the details of grain flow and the position of mechanical test pieces and stating the minimum mechanical properties expected from such test pieces. of a metal 2.2118 Corrosion - The deterioration electrochemical reaction with its environment. 2.2119 Intergranular grain boundaries. Corrosion - by chemical perferentially or at Corrosion 13 occurring lSht41(%urtII%)-1979 2.2.M Pitting Cawosian- Localized .corresion~resulting&~small pits or craters in metal s&&e. 2.2.121 Stress Corrosion Crackit,g- Failure by cracking resulting from directional attack caused by the simuitaneow interaetion of sustained. tensile stress at an exposed ~urbee with the chemical or electrochemical effects of the surface environment. 14 BUREAU Headquarters: OF INDIAN STANDARDS Manak Bhavan, 9 Bahadur Shah Zafar Marg. NEW DELHI 110002 Telephones: 331 01 31, 331 13 75 Regional Offices: Central : Manak Bhavan, 9 Bahadur Shah Zafar Marg. NEW DELHI 110002 *Eastern : 1 /14 C. I. T. Scheme VII M, V. I. P. Road, Maniktola. CALCUTTA 700054 Northern : SC0 445-446, Sector 35-C, CHANDIGARH 160036 Telegrams: Manaksanstha ( Common to all Off ices ) Telephone 331 01 31 I 331 13 75 36 24 99 I 21843 3 16 41 41 24 42 Southern : C. I. T. 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